Recently, user's demands on a high quantity and high quality multimedia service are continuously increasing in broadcasting and wireless communication fields. In order to satisfy the demands by a restricted frequency resource, technologies which improve the frequency efficiency as compared with a transmission technology of the related art are necessary. As one of the above-mentioned technologies, a faster than Nyquist (FTN) technique draws attention.
In a transmitting method which is used in a broadcasting and communicating system of the related art, a Nyquist pulse which is designed such that no interference is generated between adjacent transmitting symbols is used. However, according to the FTN technique, the transmitting symbol is transmitted at a cycle which is shorter than that in the related art in order to improve transmission efficiency. Therefore, inter symbol interference is generated between the transmitting symbols.
An amplitude and a phase of a transmitting signal are distorted due to multi-path fading while the transmitting signal passes through a channel, so that the transmitting signal needs to be transmitted by adding the pilot symbol to compensate the distortion in the receiver. Further, the pilot symbol is necessary to synchronize the signals in the receiver.
However, according to the FTN technique, the symbol is transmitted at a shorter cycle than that of the related art. Therefore, data symbols which are adjacent to the pilot symbol affect the pilot symbol so that the pilot symbol is distorted. The above-described distortion causes a problem in that a distorted pilot symbol is transmitted. Further, a distortion degree of the pilot symbol is not constant, but varies depending on a value of the data symbol which is adjacent to the pilot symbol. Therefore, it is difficult to estimate how much the pilot symbol is distorted in the receiver. The receiver performs channel estimating and synchronizing processes under the assumption that a pilot symbol which is not distorted is transmitted, so that the channel estimating and synchronizing performances may be significantly degraded.